The present invention relates to bimetal temperature switches.
In many applications it is crucial to know whether the temperature in a reactor., vessel or engine has exceeded a predetermined set point. When such an event occurs, an alarm should sound or some other action should occur. A simple yet effective way to accomplish this function is through the use of thermostatic bimetal strip.
A thermostatic bimetal strip is defined as a composite material, made up of two or more metal strips fastened together. This composite, because of the different expansion rates of the component strips, tends to change curvature when subjected to a temperature change.
With one end of the strip fixed, the other end deflects when subjected to a temperature change. The bimetal strip is positioned so that after it deflects a certain amount it makes contact with a lead and thereby completes a circuit. The point at which the circuit is completed corresponds to certain deflection of the bimetal strip and a certain temperature. This circuit is connected to a warning light, alarm annunciator or some other device to indicate that the temperature has been exceeded.
Although devices using this principal are well known, there are problems that occur with known devices. Usually the bimetal strip is crimped into a copper temperature well. Because of this design, the bimetal element is subject to "shift" prior to use. The shift in the strip alters the high or low temperature signal that the device measures, thereby giving inaccurate readings. The shift can occur because the copper temperature well can deform slightly due to handling prior to installation. This shifts the position of the bimetal strip. Another problem of the known devices is that a separate hole into the vessel or engine needs to be provided to mount the copper temperature well. The present invention solves these problems in a unique and economical manner.